The invention relates to a throttle body with a housing comprising a housing cover and a housing body and with a through throttle aperture for a throttle butterfly arranged on a throttle-butterfly shaft, the throttle-butterfly shaft being drivable as a function of specifiable parameters by means of an electronic system arranged in the housing by an electric actuator likewise arranged in the housing and having a drive shaft, the position of the throttle-butterfly shaft being detectable by means of a position detection device arranged in the housing.
To control the quantity of fresh gas to be fed to the combustion engine of a motor vehicle, use is generally made of throttle bodies. Throttle bodies comprise a housing with a through throttle aperture and a throttling member arranged in the throttle aperture. The throttling member is generally a throttle butterfly, which is arranged pivotably on a throttle-butterfly shaft mounted in the housing. The throttle butterfly arranged on the throttle-butterfly shaft assumes a certain position in the throttle aperture to allow through a certain quantity of fresh gas. For this purpose, the throttle-butterfly shaft, on which the throttle butterfly is arranged, can be activated mechanically or electronically.
In part of the range, e.g. the idling range, the throttle butterfly of a throttle body can be movable by an actuator and, in the remainder of the range, can be movable with the aid of a wire cable coupled to the accelerator pedal of the motor vehicle. As an alternative, however, the throttle butterfly can also be movable by an actuator over its entire range of adjustment. In these last-mentioned systems, there is no mechanical connection between the desired-value input, in particular the accelerator pedal, and the throttle butterfly. Triggered by the depression of the accelerator pedal, the power demand in these xe2x80x9celectronic engine output controlxe2x80x9d or xe2x80x9cdrive-by-wirexe2x80x9d systems is converted into an electrical signal. The electrical signal is fed to a control unit, which, in turn, produces an activation signal for the actuator from the electrical signal.
To avoid faults during the transmission of the activation signal from the control unit to the actuator of the throttle-butterfly shaft in electronic engine output control systems, there are throttle bodies in which the control unit for the actuator is integrated into the housing of the throttle body. In this case, the control unit can be integrated into an electronic system arranged in the housing. In this arrangement, the electronic system is provided for further functions of the throttle body, e.g. for activating position monitoring of the throttle-butterfly shaft and detecting and storing data relating to the throttle body.
For the purpose of monitoring the position of the throttle-butterfly shaft, a position detection device is generally provided. There are position detection devices that detect the current position of the throttle-butterfly shaft by contact with the throttle-butterfly shaft. Alternatively, there are position detection devices that detect the respectively current position of the throttle-butterfly shaft in a contactless manner. Contactless position detection devices generally have a particularly large space requirement since they have to be arranged in alignment with the throttle-butterfly shaft, as a result of which the axial length of the throttle body housing is generally increased considerably.
The object underlying the invention is to specify a throttle body of the abovementioned type, the housing of which has a particularly small space requirement and which furthermore has a contactless position detection device for the throttle-butterfly shaft.
According to the invention, this object is achieved by virtue of the fact that the electronic system for the electric actuator is arranged in the housing cover, and the position detection device comprises a Hall-effect magnet arranged on the drive shaft and a Hall-effect sensor arranged directly next to the Hall-effect magnet for the purpose of detecting the position of the throttle-butterfly shaft.
The invention starts from the consideration that the housing of the throttle body has a particularly small space requirement if the elements of the throttle body are arranged in a particularly compact way. A contactless position detection device for a throttle-butterfly shaft of a throttle body can also be arranged with a particularly small space requirement in the housing of the throttle body if it detects the current position of the throttle-butterfly shaft indirectly, rather than directly. A particularly large amount of space is saved if the position detection device is connected functionally to other elements of the throttle body. For this purpose, the position detection device comprises a Hall-effect magnet arranged on the drive shaft of the actuator and a Hall-effect sensor arranged directly next to the Hall-effect magnet.
The electric actuator is advantageously an electrically commutated motor. An electrically commutated motor is less prone to wear than an electric motor with carbon brushes and furthermore is particularly quiet. Owing to the absence of friction associated with carbon brushes, the electrically commutated motor takes less current, has a comparatively low power loss and develops less heat during operation than an electric motor with carbon brushes. Moreover, an electrically commutated motor has shorter actuating times and a better response than an electric motor with carbon brushes. Finally, an electrically commutated motor is simpler to assemble since the complex assembly of the brush holder plate is eliminated.
The electronic system for the electric actuator is advantageously arranged on a board in the housing cover. A board is particularly simple to fit in the housing cover of the housing of the throttle body and furthermore has a particularly small overall height.
The evaluation module for the output signals of the Hall-effect sensor is advantageously arranged on the board in the housing cover.
In addition to the first electronic system of the electric actuator, a second electronic system for electric appliances arranged outside the housing is advantageously arranged in the housing cover of the housing of the throttle body, the second electronic system being arranged on the board together with the first electronic system. As a result, the electronic system of the throttle body does not need to be coupled separately to a so-called electronic engine control system. As a result, the path of the signal of the Hall-effect sensor to the electronic evaluation system is particularly short. Moreover, the current position of the throttle butterfly can then be coordinated in a particularly simple manner, by means of the signal of the Hall-effect sensor, with further parameters of the engine in which the throttle body is arranged.
The housing cover is advantageously composed predominantly of plastic, electrical connection means, by means of which the first electronic system for the electric actuator and the second electronic system for the appliances arranged outside the housing can be brought into contact at least with the electric appliances arranged outside the housing, being integrated into the housing cover. Connection means of this kind can be integrated into the housing cover in a particularly simple manner if the latter has been produced by injection molding. Moreover, the contacts for the electronic system can then be integrated into the housing cover of the housing of the throttle body at fixed predeterminable points.
The electric appliances are advantageously arranged in a combustion engine of a motor vehicle. Thanks to the spatial connection between the electronic system for the actuator and the electronic system for the electric appliances arranged outside the housing, the combustion engine has a central electronic system, as a result of which the number of elements of the combustion engine is particularly small. Moreover, faults due to signal transmissions from the first to the second electronic system are virtually eliminated.
The electric appliances arranged outside the housing are advantageously an ignition appliance and/or an injection appliance and/or an oil-level measuring appliance and/or an air-mass regulating appliance and/or a power supply appliance.
The throttle-butterfly shaft can advantageously be driven by the electric actuator via a reduction gear connected to the actuator shaft, the position detection device being arranged at one end of the actuator shaft and the reduction gear being arranged at the other end of the actuator shaft. The spatial separation of the gear and the position detection device is a particularly reliable means of ensuring that no abraded material from the gear gets into the position detection device.
The arrangement of a contactless position detection device on the actuator shaft of an electric actuator for the throttle-butterfly shaft of the throttle body enables the position detection device to be arranged in the housing of the throttle body with a particularly small space requirement. Here, the respectively current position of the throttle-butterfly shaft is detected indirectly via the drive shaft of the actuator.